Dieter Rams and Dietrich Lubs designed the first of Braun's ET calculator series in the late 1970s, when, after the invention of the microprocessor, pocket calculators were becoming ever smaller, less expensive to produce, and more widely available to the public. Rams's ET55 of 1980 further refines his earlier calculator designs. An iconic example of his pared-down design philosophy, the ET55's understated elegance and exacting precision of detail made it an immediate success.